Alright, it was a long time since I read it but it was this story where this guy gets sent into space with this super advanced ai and stuff that he gradually teaches over the course of many years. During the journey he goes to sleep and wakes up in some amount of years intervals. He eventually gets into contact with Earth again and sends a video of him explaining himself and his decisions (This part is a bit iffy but I know for sure he sent the message). Afterwards they alter the video into having him appear as the bad guy, I believe they call him a terrorist. However, the AI of the ship (Don't remember the name of her but I know he falls in love her and and I think her with him) puts the original message hidden in the message so even if they alter it the true message is still there. Everyone finds out resulting in the destruction of planet by nuclear warfare, resulting in him having a breakdown.